The rapid spread of SARS-CoV-2, a novel coronavirus that emerged in late 2019, and the resulting COVID-19 pandemic, has been labeled as a public health emergency of international concern by the World Health Organization. Individuals with diabetes mellitus are at high risk for severe manifestations of the disease, with mortality of up to 35% in China. DPP-4 inhibitors (saxagliptin, sitagliptin, vildagliptin, alogliptin and linagliptin) are used worldwide to treat type 2 diabetes. DPP-4 is also known as lymphocyte cell surface protein, or CD26, that plays an important role in T-cell immunity DPP-4/CD26 is present and active in the lungs and is expressed constitutively by lung fibroblasts, on which it exerts proliferative effects. It is also a marker of fibroblast migration and functional activation, including collagen synthesis and inflammatory cytokine secretion. Inflammatory lung diseases are characterized by high expression levels of DPP-4/CD26 that could increase the inflammatory response, increasing the severity of lung injury.At this point, it is critical to observe the evolution of COVID-19 disease in patients with diabetes using DPP-4 inhibitors. DPP-4 inhibitors may worsen or in some cases ameliorate the evolution of lung injury in patients with diabetes mellitus. Understanding this relationship could help to improve the management of COVID-19 infection in patients with diabetes mellitus using DPP-4 inhibitors.